Firth Brown harness tester

I was given an old Firth Brown 'Hardometer' hardness tester the other
day. Sadly it has suffered from years of neglect, most of which can
simply be remedied even if it will never have gleaming chrome again.
It is short of the guts of the microscope - I reckon I can find a
suitable substitute there - and the 1mm hard ball itself is missing.
Anyone here know a) proper operating procedure for these things, b) is
the plug on the side of the working head, with a fancy chrome tee
handle, an oil filler cap or something else? c) Where can I find a
1mm hard ball to suit? I do have the fitting which is supposed to
contain the ball (made for easy changing).
Reply to
Tim Leech
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I don't recognise this bit of kit, but I think ordinary "ball bearing" balls in instrument bearings go down to about this size. Try Bearing Services or Google for "ball bearing" or "rolling element bearing". There's an outfit called Spheric who make high precision balls in metal and sapphire. These are used in Renishaw type "touch probes". Even if you can't get the exact size, the conversion formula are around.
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